initialize

排序算法/归并排序/README.md

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+请移步[蒂米的博客](http://timd.cn/2017/10/16/merge-sort/)。  

排序算法/归并排序/merge_sort.py

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+class MergeSort:
+    @staticmethod
+    def merge(array, start, mid, end):
+        if not (start <= mid <= end):
+            return
+        i, j = start, mid + 1
+        temp_list = [None] * (end - start + 1)
+        cursor = 0
+
+        while i <= mid and j <= end:
+            if array[i] <= array[j]:
+                temp_list[cursor] = array[i]
+                i = i + 1
+            else:
+                temp_list[cursor] = array[j]
+                j = j + 1
+            cursor = cursor + 1
+
+        while i <= mid:
+            temp_list[cursor] = array[i]
+            i = i + 1
+            cursor = cursor + 1
+
+        while j <= end:
+            temp_list[cursor] = array[j]
+            j = j + 1
+            cursor = cursor + 1
+
+        for ind, element in enumerate(temp_list):
+            array[start + ind] = element
+
+    @classmethod
+    def merge_sort_recursive(cls, array, start=None, end=None):
+        if start is None:
+            start = 0
+        if end is None:
+            end = len(array) - 1
+        if start >= end:
+            return
+
+        mid = (end + start) / 2
+        cls.merge_sort_recursive(array, start, mid)
+        cls.merge_sort_recursive(array, mid+1, end)
+        cls.merge(array, start, mid, end)
+
+    @classmethod
+    def merge_sort(cls, array):
+        step = 1
+        while step <= len(array):
+            step = step * 2
+            for start in range(0, len(array), step):
+                end = start + step - 1
+                mid = (start + end) / 2
+                if end >= len(array):
+                    end = len(array) - 1
+                    mid = min(start + step / 2 - 1, end)
+                cls.merge(array, start, mid, end)
+
+if __name__ == "__main__":
+    import random
+    lst = range(30)
+    random.shuffle(lst)
+    print lst
+    MergeSort.merge_sort(lst)
+    print lst
+